Dye Microenvironment

ABSTRACT

An optimized photochromic dye microenvironment isolated from and dispersed within a distinct host phase.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/017,150 filed Jun. 25, 2014 entitled Photochromic DyeMicroenvironment, which is hereby incorporated herein by reference inits entirety.

FIELD OF THE INVENTION

The present invention pertains to colorants and, more particularly, tothe optimization of colorant characteristics within a host medium.

BACKGROUND OF THE INVENTION

Photochromic dye molecules absorb light, e.g. UV light, which leads to athermally reversible conformation change or isomerization, frequently byring opening, which results in a color change. This bond rearrangementcauses the colored form of the dye molecule to occupy a different,frequently larger, volume than the leuco, or colorless form of the dye.

Photochromic dye behavioral characteristics, including expressed coloror activation and fading rates, all depend on specific details of thestructure of the dye molecule. Consequently, dye color, activation andfading rates are difficult to control independently by changing specificdye molecule structural attributes, i.e. altering a substituent on thedye molecule to increase fading speed will also generally change thecolor of the activated dye molecule as well, and vice versa. Fine-tuningdye characteristics through synthesis of different dye structures andevaluating such behaviors is a long and arduous task, and critically,these characteristics are difficult to predict accurately.

Accordingly, there exists a need in the art for highly controllable,robust techniques for controlling and optimizing photochromic dyebehavior in diverse applications and environmental conditions.

SUMMARY OF INVENTION

One embodiment of the present invention provides photochromic dyeoptimization and characteristic control that are substantially moreconvenient to practice than dye molecule synthesis, and which can beused to independently alter and control the behavioral attributes of agiven dye. Specifically, by controlling the microenvironment around thedye, its color and activation/fading rates can be adjusted as desired.

Certain embodiments of the present invention further provide forisolation of the dye microenvironment from a surrounding or host matrix.In certain applications, the desired components of the dyemicroenvironment may limit the performance characteristics of a bulkmatrix in which the dye-microenvironment is employed. By isolating thedye, surrounded by the preferred microenvironment, as a dispersed phasewithin a continuous host matrix phase designed for the end useapplication, the desired performance characteristics of both the dye andthe host matrix can be optimized independently.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a graph showing examples of the optimization of dye colorresponses by manipulation of matrix glass transition temperature,according to one embodiment of the present invention.

FIG. 2 is a graph showing examples of the optimization of dye activationand fading rates by manipulation of matrix glass transition temperature,according to one embodiment of the present invention.

FIG. 3 is a graph showing examples of the optimization of dye fade ratesby manipulation of matrix glass transition temperature, according to oneembodiment of the present invention.

FIG. 4 is a graph showing examples of the optimization of dye colorresponses and half-lives by manipulation of matrix solvents, accordingto one embodiment of the present invention.

FIG. 5 is a graph showing examples of the optimization of dye colorresponses and half-lives by manipulation of matrix solvents, accordingto one embodiment of the present invention.

FIGS. 6A and 6B are graphs showing examples of the optimization of dyecolor responses by manipulation of polar cosolvents, according to oneembodiment of the present invention.

FIG. 7 is a graph showing examples of the optimization of dye colorresponses by manipulation of HEMA in an acrylate copolymer, according toone embodiment of the present invention.

FIGS. 8A-8C are graphs showing examples of the optimization of dyeactivation and fading by manipulation of the matrices at differenttemperatures, according to one embodiment of the present invention.

FIG. 9 is a cross-sectional view of a dynamically responsivedye/colorant layer according to one embodiment of the present invention.

FIG. 10 is a cross-sectional view of a disperse phase according to oneembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

For the sake of clarity, in the following disclosure, the term “dye” or“colorant” broadly includes compounds that absorb visible light,exhibiting permanent or temporary (dynamic) color in response to aneternal stimulus such as UV light and, more particularly, molecules andcompounds having photochromic, electrochromic, liquid crystal,non-photochromic coloration, and tinting characteristic ortype-characteristics.

The term “microenvironment” refers to the components in the immediatevicinity or that are the nearest neighbors surrounding a dye orcolorant. These components are generally considered to be close enoughto the dye or colorant to influence the behavior of the dye or colorantthrough direct contact, such as hydrogen bonding, or through specialinteractions, such as dipole-dipole interactions. The dyemicroenvironment can also be described by the term “solvation shell”,commonly used to describe the volume of material immediately surroundingan ion or molecule in a solution. The components of the“microenvironment” can comprise polymer segments, e.g. portions of largemolecules; plasticizers, e.g. oligomers or other molecules which canmodify the behavior of the polymer segments; and/or solvent moleculeswhich can further modify mobility of polymer segments, plasticizersand/or dyes or colorants or portions thereof.

For example, in a salt solution, as in common table salt, sodiumchloride (NaCl), or a sugar solution, as in sugar in coffee, the waterdissolves (separates) the individual ions (Na+, Cl−) or glucosemolecules (C₆H₁₂O₆) of the crystals by providing stabilizinginteractions, either dipole-dipole interactions through space, orhydrogen bonding through direct contact, making it energeticallyfavorable for the crystals to disintegrate into individual ions ormolecules.

The term “dye matrix” or “colorant matrix” is a general term andincludes the microenvironment and other components which may be presentboth immediately surrounding and/or further away from the dye molecules.The dye matrix can influence dye response. For example, the dye matrixmay influence a dye's activation and fading rates through the dyematrix's glass transition temperature as described in detail below. Thedye matrix may also influence dye responses through effects orinteractions based on chemical functional groups, which may be presentand interact with the dye molecule through dipole-dipole or hydrogenbonding interactions.

The term “dispersed phase” refers to a separate and discreet regionwithin a continuous phase which comprises of a dye or colorant and the“colorant microenvironment” and the “colorant matrix.” By way ofanalogy, consider a molded gelatin fruit salad. The fruit is analogousto the dispersed phase and the gelatin would analogous to the continuousphase. Another example is the aggregate within concrete; the aggregateor pebbles are analogous to the dispersed phase and the cement isanalogous to the continuous phase.

The term “continuous phase” and “host matrix” are interchangeable termsand refer to the compositions or the bulk phases, e.g. the continuouspolymer phase, surrounding or containing the individual dispersed phasestructures or particles in which one of more dye molecules aredistributed or dissolved. The continuous phase is farther away from thedye molecules than the solvation shell, and will have little, if any,direct influence on the dye behavior, as long as the dye is within aseparate, dispersed phase microenvironment. In order for the bulkproperties of the continuous host matrix phase thermo-mechanicalproperties to dominate the matrix behavior, the continuous phase mustgenerally be present in an equivalent or larger volume percent than thedispersed phase.

Optimization of Dye Activity

Broadly speaking, in certain embodiments of the present invention,photochromic dye microenvironment characteristics are manipulated toindependently control photochromic dye color, temperature sensitivity,activation (k₁) and fading or decay (k₂) rates, among othercharacteristics.

One controllable characteristic of the photochromic dye microenvironmentis the glass-transition temperature of the dye matrix directlysurrounding the photochromic dye. Dye matrix glass-transitiontemperature influences a dye molecule's response rate for activation(k₁) and decay (k₂).

For example, in a dye matrix with a glass-transition temperaturesubstantially higher than the ambient temperature, at the timeultraviolet, UV, radiation is absorbed by the leuco dye form, theability of the local polymer segments around the dye molecule to “moveout of the way” is reduced, inhibiting the ability of the dye moleculeto ring-open to the colored form (reducing k₁). Importantly, this alsointerferes with its ability to undergo the reversible ring closure tothe original leuco form (reducing k₂). Conversely, when theglass-transition temperature of the dye matrix is substantially lowerthan the ambient temperature at which UV activation occurs, segmentalmotion in the dye matrix is faster, and the dye molecule can changeconformation to the colored form or back to the leuco form with lessresistance by the immediate environment (increasing both k₁ and k₂).

A second controllable characteristic of photochromic dyemicroenvironment is the polarity of the dye matrix directly surroundingthe photochromic dye. Dye matrix polarity, in part, influences the colorresponses of a particular dye. The dye matrix polarity influences theintensity of color response, e.g. more polar (or hydrogen bonding)environments lead to more neutral colors.

Not to be bound by theory, this controlled characteristic, in part,influences dye molecule performance by the way the dye moleculeinteracts with those molecules immediately surrounding it, a kind ofsolvatochromism. The dye matrix molecules closest to the dye molecule,those within the “solvation shell”, can chemically interact with thefunctional groups present in the dye molecule. These interactions can bethrough space, as in dipole-dipole interactions, and by “directcontact”, for example through hydrogen bonding. In both cases, theseinteractions subtly modify the details of electron distribution withinthe dye molecule, which influences the wavelengths absorbed by the dye,changing both its UV and visible spectra in the leuco and colored forms.

The microenvironment influences the intensity of the dye color response,where a more strongly interacting solvation shell (polar or hydrogenbonding) leads to more neutral colors, and in some cases can influencedye activation (k₁), and particularly the decay rate (k₂, indicated byhalf-life t_(1/2)) of the dye.

Dye Optimization Example 1 Effects of Model Dye Matrix Glass TransitionTemperature on Dye Activation and Fade Rates

A single component photochromic naphthopyran dye was tested in laminatesprepared from a series of model acrylic copolymers comprising n-butyland t-butyl acrylate monomer mixtures, dye color responses were verysimilar, but dye activation and fading rates depended strongly on bothtest temperature and matrix glass-transition temperature. Tests wereperformed at 0, 10, 22 and 35 degrees Celsius; matrix glass transitiontemperature ranged between −42° C. and +47° C. The results aregraphically summarized in FIGS. 1, 2 and 3.

These results clearly demonstrate (a) that dye matrix glass-transitiontemperature has little effect on color, and (b) that dye matrixglass-transition temperature must be well below the test temperature toexhibit the fastest activation and fading rates.

Dye Optimization Example 2 Influence of Chemical Environment on DyeResponse; Solvent Models

A single component photochromic naphthopyran dye was tested in a varietyof solvents that presented different chemical environments (0.20 weightpercent dye and 1 millimeter path length), it exhibited a wide range ofcolor responses as illustrated in FIG. 4, as well as a 3-fold range offading rates, which are characterized by half-life (t_(1/2))″. In anygiven solvent, whether tested at 0 or 22 degrees Celsius, the colorexhibited was very similar, but the fading rates all decreased at thelower test temperature.

Similarly, another single-component photochromic dye tested in selectedsolvents exhibited different color responses with half-lives that variedover a 4-fold range (FIG. 5).

In two mixed solvent systems (THF with methanol or water added),systematic changes in dye color were observed as the polar cosolventlevel increased. No significant differences were observed for dyeactivation rates or fading half-lives (FIGS. 6A and 6B):

The above examples demonstrate that in more polar environments, or thosecapable of strong hydrogen bonding, the dye exhibits the most neutralcolors, while in less polar environments the dye is more stronglycolored, as indicated by the length of the radius (a* and b* values) inthe color space plots.

Dye Optimization Example 3 Influence of Chemical Environment on DyeResponse; Polymer Matrix Models

A series of terpolymers with similar low glass-transition temperature(−25±4 degrees Celsius), but with varying polarity/hydrogen bondingcapabilities, were prepared from mixtures of n-butyl/t-butyl acrylateand 2-hydroxyethyl methacrylate (HEMA). The dye was added to thesecopolymer solutions, which were laminated between polycarbonate filmsand evaluated for color response (FIG. 7) by UV-visiblespectrophotometry, activation and fading rates at 0, 10, 22, and 35degrees Celsius (FIGS. 8A-8C). The 10 molar percent HEMA film isexcluded from the figure for clarity.

Dye activation and fading rates (t_(1/2)) were similar for all laminatesat any test temperature (FIG. 8A-8C), but the higher the HEMA content,the more neutral was the color exhibited (smaller values of a* and b*):the color trends observed in the mixed solvent models translated to thepolymeric matrices.

Dye Matrix

Certain embodiments of the present invention employ compositionscomprising one or more dyes and a dye matrix comprising one or moreadditives chosen to independently control and modify the color and theactivation and fading response of the dye(s), and one or more dyemodifiers.

Colorants or dyes may be either permanent or dynamic. Permanentcolorants include traditional dyes and pigments, including metameric andmagnetic pigments, which can change color or alignment under differentlighting or magnetic environments. Permanent colorants are generallysoluble dyes but may also be pigments having sufficiently small particlesize, for example, less than 10 nanometers. Such permanent colorants mayalternatively be incorporated within the continuous phase withconsideration being taken to the particle size requirements andcontrolling hazing.

Dynamic colorants may, for example, be any suitable photochromiccompounds. For example, organic compounds that, when molecularlydispersed, as in a solution state, are activated (darken) when exposedto a certain light energy (e.g., outdoor sunlight), and bleach to clearwhen the light energy is removed. They can be selected from benzopyrans,naphthopyrans, spirobenzopyrans, spironaphthopyrans, spirobenzoxzines,spironaphthoxazines, fulgides and fulgimides. Such photochromiccompounds have been reported, for example, in U.S. Pat. Nos. 5,658,502,5,702,645, 5,840,926, 6,096,246, 6,113,812, and 6,296,785; and U.S.patent application Ser. No. 10/038,350, all commonly assigned to thesame assignee as the present invention and all incorporated herein byreference.

Among the photochromic compounds identified, naphthopyran derivativesexhibit good quantum efficiency for coloring, a good sensitivity andsaturated optical density, an acceptable bleach or fade rate, and mostimportantly good fatigue behavior for use in eyewear. These compoundsare available to cover the visible light spectrum from 400 nanometer to700 nanometer. Thus, it is possible to obtain a desired blended color,such as neutral gray or brown, by mixing two or more photochromiccompounds having complementary colors under an activated state.

In certain embodiments, the use of variously colored dyes in specificmicroenvironments which alter the color of the dyes so as to produceneutral grey colors when activated by virtue of the small a* and b*values observed in the specific microenvironments is achieved.

Suitable dyes include naphtho[2,1b]pyrans and naphtho[1,2b]pyransrepresented by the following generic formula:

In certain embodiments of the present invention, the colorants includeone or more photochromic dyes and optionally, one or more permanent dyesand/or pigments. In certain embodiments, the colorants only includepermanent dyes and/or pigments.

In certain embodiments of the present invention, the dye matrix glasstransition temperature is tuned to maximize the dye optical density(optimize the dye dark state) according to the desired applicationtemperature. The dye matrix may, for example, comprise (co)polymers ofone or more (co)monomers with structural attributes capable ofindependently modifying the color, activation and fading response of thedye(s) through glass transition temperature and polarity/hydrogenbonding characteristics. For example, the dye matrix (co)polymers may,for example, comprise (co)monomers that provide (co)polymers with aglass transition temperature selected to provide activation and fadingrates optimized for the end use application.

The (co)monomers from which the dye matrix (co)polymers are synthesized,employ such structural attributes as hydroxyl and ether groups (R—OH andR₁—O—R₂), ester groups (R_(a)-[C═O]-OR_(b)), ketone groups(R_(a)-[C═O]-R_(b)), amine groups (R_(a)NHR_(b)), nitro groups (R—NO₂),carbonate groups (R_(a)O—[C═O]-OR_(b)), amide groups(R_(a)NH—[C═O]-R_(b)), urethane groups (R_(a)NH—[C═O]-OR_(b)), ureagroups (R_(a)NH—[C═O]-NHR_(b)), imide groups(R_(a)-[C═O]-NH—[C═O]-R_(b)), hydrazide, semicarbazide and semicarbazonegroups (R_(a)-[C═O]-NH—NHR_(b), R_(a)—NH—[C═O]-NH—NHR_(b) andR_(a)NH—[C═O]-NH—N═CR_(b)R_(c)), thiol and thioether groups (R—SH andR_(a)SR_(b)), sulfoxide and sulfone groups (R_(a)-[S═O]-R_(b) andR_(a)-[SO₂]-R_(b)), ester groups (R_(a)-[SO₂]-OR_(b)), phosphines andphosphine oxides (R_(a)R_(b)R_(c)P and R_(a)R_(b)R_(c)P═O), esters(R_(a)[R_(b)O]-α[═O]-OR_(c)), phosphate esters ([RO]₃P═O), and the like,which are polar (have high dielectric constants) and which can interactwith, for example, the photochromic dyes by donating and/or acceptinghydrogen bonds. As herein used, the structural definitions of “R” groupsis in accordance with that of organic and polymer chemistry. “R” is ashort-hand convention used to represent generic structures, whichstructures predominantly contain carbon and hydrogen atoms bondedtogether in unspecified configurations. In this context, the groups Rare independently chosen and can be the same or different, and in manycases, either, but not both R groups, can be a hydrogen atom.

The (co)polymers that employ the color modifying polar structuralattributes may be present as connectors between two or more monomersfrom which the polymer is built, or preferably, which connect two ormore structural groups within the (co)monomers, or more preferably, asend groups within the (co)monomers.

Certain embodiments of the present invention further employ additivescontaining polar structural attributes capable of independentlymodifying the color, activation and fading response of the dye(s)through their modification of the polymer glass transition temperatureand possess high local polarity/hydrogen bonding characteristics. Suchadditives may act to lower or raise the glass transition temperature ofthe polymer dye matrix. Such polar structural attributes includehydroxyl and ether groups (R—OH and R₁—O—R₂), ester groups(R_(a)-[C═O]-OR_(b)), ketone groups (R_(a)-[C═O]-R_(b)), amine groups(R_(a)NHR_(b)), nitro groups (R—NO₂), carbonate groups(R_(a)O—[C═O]-OR_(b)), amide groups (R_(a)NH—[C═O]-R_(b)), urethanegroups (R_(a)NH—[C═O]-OR_(b)), urea groups (R_(a)NH—[C═O]-NHR_(b)),imide groups (R_(a)-[C═O]-NH—[C═O]-R_(b)), hydrazide, semicarbazide andsemicarbazone groups (R_(a)-[C═O]-NH—NHR_(b), R_(a)—NH—[C═O]-NH—NHR_(b)and R_(a)NH-[C═O]-NH—N═CR_(b)R_(c)), thiol and thioether groups (R—SHand R_(a)SR_(b)), sulfoxide and sulfone groups (R_(a)-[S═O]-R_(b) andR_(a)-[SO₂]-R_(b)), ester groups (R_(a)-[SO₂]-OR_(b)), phosphines andphosphine oxides (R_(a)R_(b)R_(c)P and R_(a)R_(b)R_(c)P═O), esters(R_(a)[R_(b)O]-α[═O]-OR_(c)), phosphate esters [RO]₃P═O), and the like,which are polar (have high dielectric constants) and which can interactwith the dynamically responsive dyes by donating and/or acceptinghydrogen bonds.

In certain embodiments of the present invention, the dye matrix furtheremploys one or more modifiers. There is no restriction to the use of asingle microenvironment modifier in the dispersed phase. More than onetype of modifier-containing dispersed phase can be present within thecontinuous phase, with each type comprise one or more photochromic dyes,permanent dyes or pigments to further modify the color, one or moremodifiers to alter the dye microenvironment and the color responsecharacteristics of the photochromic dye or dyes. Thus, the dispersedphase can be comprise a mixture of dispersed phases, each type with adifferent characteristic color, temperature sensitivity, activation orfading rate, based on the combination of different modifiers with thesame or different colorants. Not only can this provide an optimizedcolor, but also enables the rate of change between the activated andnon-activated states to be optimized. Use of such dispersed phases canprovide articles with no or some color under normal visible light, whichadopt an additional color after UV irradiation, and which will fade overtime after removal of the activating UV light back to the originalcolorless or colored state.

Two principal types of dye modifiers may be employed. One type can bebroadly described as “solvents”, which are electrically neutralmolecules that are generally liquids, but which may also be semisolidsor solids, while the other type is broadly defined as ionic compounds(salts), which are generally solids, but which may also be liquids(“ionic liquids”). These modifiers are compatible with the photochromicand traditional permanent dyes in that they are substantially misciblewith them and do not form a separate phase. They can be used separatelyor in mixtures as desired to accomplish the final appearance andbehavior of the separate dye-containing phase.

Solvent type of modifiers can include classic liquid solvents such asthe common alcohols, ethers, acids, esters, aliphatics, aromatics,amines and the like. Note that classic solvents generally possess lowermolecular weights, and are further characterized by boiling point. A lowboiling point solvent is fugitive, and a high boiling point solvent ispersistent. Fugitive solvents will readily evaporate under mildconditions and tend to have lower molecular weights, typically less thanabout 200 Daltons, while persistent solvents will not readily evaporateand tend to have higher molecular weights, typically above 200 Daltons.

In certain embodiments, the dispersed phase contains solvent typemicroenvironment modifiers primarily comprising combinations of theelements carbon (C), hydrogen (H), oxygen (O), nitrogen (N), sulfur (S),and phosphorus (P) in configurations which have permanent dipole momentsor which are capable of donating and/or accepting hydrogen bonds.

Additionally, persistent solvents may possess specific structuralattributes such as high polarity or a strong tendency to form hydrogenbonds, which will allow a lower molecular weight material to have anexceptionally high boiling point for its molecular weight. Two materialsthat demonstrate this concept include glycerin, which possesses threealcohol (R—OH) groups that contribute both high polarity and a strongtendency to form hydrogen bonded networks, has a low molecular weight ofonly 92 Daltons, and a boiling point of 290 degrees Celsius(persistent); and heptane, which is neither polar nor capable of forminghydrogen bonds, has a similar low molecular weight of 100 Daltons and aboiling point of only 98 degrees Celsius (fugitive).

Additional suitable modifiers may include 1,4-butand diol, benzylalcohol, butyl 3-hydroxybutyrate, hexadecane, dimethyl sulfoxide,sulfolane, N,N-dimethylformafide, cyclohexanone, methyl 3-heptanone,1-(2-hydroxethyl)-2-pyrrolidone, chlorobenzene,4-hydroxly-4-methyl-2-pentanone, propylene glycol monomethyl ether, andtrihexylamine.

Also falling within this class are materials generically known as“plasticizers”, which possess higher molecular weights, typically morethan about 300 Daltons, and which are known to soften polymers.Plasticizers may be liquid, resinous, semisolid or even solid, with thekey characteristic of total miscibility with the polymers theyplasticize. Additional members of this class include oligomers, such aspolyethers, polyesters, polycarbonates, polyamides and the like, whichhave molecular weights greater than about 500 Daltons, depending on themonomer structures and number of monomers incorporated in the oligomer.Suitable plasticizers include butyl stearate, butyl benzonate, glycerolmonoricinoleate, diisononyl phthalate, benzyl carbamate, ricinoleicacid, oleic acid, polypropylene glycol 1000, and trimethylolpropaneethoxylate.

Examples of chemical functional groups present in effective photochromicdye solvent type modifiers include hydroxyl and ether groups (R—OH andR_(a)—O—R_(b)), ester groups (R_(a)-[C═O]-OR_(b)), ketone groups(R_(a)-[C═O]-R_(b)), amine groups (R_(a)NHR_(b)), nitro groups (R—NO₂),carbonate groups (R_(a)O—[C═O]-OR_(b)), amide groups(R_(a)NH—[C═O]-R_(b)), urethane groups (R_(a)NH—[C═O]-OR_(b)), ureagroups (R_(a)NH—[C═O]-NHR_(b)), imide groups(R_(a)-[C═O]-NH-[C═O]-R_(b)), hydrazide, semicarbazide and semicarbazonegroups (R_(a)-[C═O]-NH—NHR_(b), R_(a)—NH-[C═O]-NH—NHR_(b) andR_(a)NH—[C═O]-NH—N═CR_(b)R_(c)), thiol and thioether groups (R—SH andR_(a)SR_(b)), sulfoxide and sulfone groups (R_(a)-[S═O]-R_(b) andR_(a)-[SO₂]-R_(b)), ester groups (R_(a)-[SO₂]-OR_(b)), phosphines andphosphine oxides (R_(a)R_(b)R_(c)P and R_(a)R_(b)R_(c)P═O), esters(R_(a)[R_(b)O]-α[═O]-OR_(c)), phosphate esters [RO]₃P═O), and the like,which are polar (have high dielectric constants) and which can interactwith the photochromic dyes by donating and/or accepting hydrogen bonds.

The second type of modifier provides additional through space dipolarinteractions to affect the photochromic dye response attributes, and canbe introduced by addition of permanently charged (ionic) materials. Suchionic type microenvironment modifiers are generally considered saltswhich comprise two or more components, each of which possesses apermanent electrical charge and which together balance out to form aneutral material. For example, one part carries one or more positivecharges on a single atom, such as metal cations like lithium (Li^(⊕)),sodium (Na^(⊕)), potassium (K^(⊕)), calcium (Ca^(⊕⊕)) and magnesium(Mg^(⊕⊕)), or within a cluster of covalently bonded atoms, such as anammonium (R₄N^(⊕)) or phosphonium (R₄P^(⊕)) ions. The most preferredcations have a small ionic radius and high charge density, particularlylithium, sodium, magnesium and calcium cations. The other part carries asingle negative charge on a single atom, such as on the halide anionsfluorine (F^(⊖)), chlorine (Cl^(⊖)), bromine (Br^(⊖)) and iodine(I^(⊖)), or within a cluster of atoms, such as tetrafluoroborate (BF₄^(⊖)), hexafluorophosphate (PF₆ ^(⊖)), and toluene sulfonate (H₃CPhSO₃^(⊖)e), or multiple negative charges on clusters of multiple covalentlybonded atoms, such as phthalic acid dianions (Ph{—[C═O]O^(⊖)}₂), and thelike, as necessary to balance of the positive and negative charges inthe ionic modifier. For improved solubility in the dispersed phase, theanions employing low charge densities, such as bromide and particularlyiodide, tetrafluoroborate or hexafluorophosphate, or be organic, such asp-toluene sulfonate, and the like may be employed. These modifiers areused in similar molar amounts relative to the amount of photochromic dyepresent.

The amount of dye microenvironment modifiers present in the dispersedphase employed is sufficient to provide the desired degree ofmodification of activated color, for example UV activated color,formation within the article. As such, the total amount of modifierspresent is from about 100 parts-per-million per micrometer to about10,000 parts-per-million per micrometer of path length through which thelight travels to activate, for example, the photochromic dye in thearticle. In general, there will be more modifier functional groupspresent than dye on a molar basis. The amount of modifier will vary bymodifier and photochromic dye types, their molecular or functional groupequivalent weights, the extinction coefficient of the photochromic dye,the degree and type of interaction between the dye and the modifier, theamount of color change desired, the presence of other colorants such aspermanent dyes or pigments, and their extinction coefficients, and soforth. For example, the amount of dye microenvironment plasticizers andlow volatility solvents may range from zero weight percent to 100 weightpercent or from 20 weight percent to 40 weight percent.

In addition to such additives as described above modifying, for example,photochromic dye attributes of color and activity, these additives canalso modify the color/hue perceived for permanent dyes and pigments,providing yet another mechanism to control the appearance andperformance of the articles containing the compositions of thisinvention.

Isolation of Dye Matrix

In certain embodiments of the present invention, a dispersed phase,comprising components chosen to control a dye color and/or othercharacteristics, is dispersed in a continuous phase, comprisingcomponents chosen to control the chemo-thermo-mechanical properties ofthe bulk composition. For the sake of clarity, the term “continuousphase” may also be understood as a “host matrix.”

In practice, the preferred microenvironment and or matrix for dyeperformance may not provide the desired performance characteristics ofthe continuous phase in the target application. For example, the fastestdye color decay rates occur in microenvironments with lowerglass-transition temperatures. However, continuous phase having a lowerglass-transition temperature may not be optimal for an elevatedtemperature use environment because of the potentially corresponding lowmechanical strength, which can lead to bulk host matrix failure undershear or other forces. Consequently, in this example, a key requirementfor performance of the dye and the host matrix are incompatible: a hostmatrix optimized to satisfy the harsh use conditions of the article maynot provide adequate performance of the photochromic dye, and viceversa.

In certain embodiments of the present invention, with reference to FIGS.9 and 10, this problem is overcome or minimized by isolating thephotochromic dye 16 and the dye microenvironment and dye matrix 18 fromthe bulk host matrix or continuous phase 14. This objective isaccomplished by dispersing the dye and its preferred microenvironmentwithin the host matrix as a separate particle or dispersed phase 12embedded or encapsulated within the continuous phase 14 which will bedependent on the application. This approach allows the two phases to beoptimized separately to meet the performance specifications of theparticular end use.

Two key requirements of the dispersed phase are that both the dye andany microenvironment components such as additives and/or modifierspresent in the dispersed phase must be permanently contained and cannotdiffuse into the continuous phase over time. Both conditions arenecessary to maintain consistent performance of the photochromic articleover time. Specific structural attributes of the dispersed phase may benecessary to prevent diffusion of the dye and modifiers out of thedispersed phase and into the continuous phase. The composition of thedispersed phase generally requires one or more colorants within a dyematrix and one or more binder materials or systems to permanentlycontain and separate the active components that generate the principaloptical effects from the continuous phase 14.

In certain embodiments of the present invention, binders can includesingle polymers, (co)polymers, mixtures of (co)polymers, includinginterpenetrating polymer networks, crosslinkers, and the like, and oneor more layers of polymers, copolymers, crosslinkers and the like, asrequired to meet the key requirements of the dispersed phaseperformance.

In certain embodiments, the binder materials themselves can furthercontribute to dye microenvironment compositions, to modify the color ofthe photochromic dye in addition to preventing the diffusion of the dyeinto the continuous phase and affect k₁ and k₂. For example, suitablebinders having a relatively high glass transition temperature include,homopoly(t-butyl acrylate), copoly(t-butyl acrylate/2-hydroxyethylmethacrylate), and polyvinyl butyral B98, separately or in combination.Exemplary suitable binders having a relatively low glass transitiontemperature include, homopoly(n-butyl acrylate), copoly(n-butylacrylate/2-hydroxyethyl methacrylate), copoly(n-butylacrylate/2-hydroxyethyl acrylate, copoly(t-buty/n-buty acrylate),copoly(ethylhexyl acrylate/t butyl acrylate), terpoly(t-butyl/n-butylacrylate/2-hydroxyethyl methacrylate), employed separately or incombination with polyvinyl butyral B98.

There is no restriction to the use of a single binder composition in thedispersed phase, nor to a single layer or outer shell of bindercomposition within any dispersed phase particle. More than one type ofbinder-containing dispersed phase can be present within the continuousphase for form a mixed or heterogeneous dispersed phased system. In amixed dispersed phased system each different type of binder-containingdispersed phase may comprise one or more photochromic dyes, permanentdyes or pigments; one or more additives and/or modifiers to alter thedye microenvironment and the color response characteristics of thephotochromic dye or dyes; and one or more binders and/or binder layers,which can further serve to modify the dye color responsecharacteristics. Accordingly, the dispersed phase can comprise a mixtureof dispersed phases, each type with a different characteristic color,temperature sensitivity, activation or fading rate, based on thecombination of different binders with the same or different colorantsand modifiers. Use of such mixed dispersed phases will provide articleswith no or some color under normal visible light, which adopt anadditional color after irradiation, and which will fade over time afterremoval of the activating light back to the original state.

The amount, type and structure of the binders present in the dispersedphase is sufficient to prevent diffusion of the microenvironmentmodifiers and colorants contained within the dispersed phase into thecontinuous host matrix phase within the article. As such, the totalamount of binder present is from about 5,000 parts-per-million permicrometer to about 20,000 parts-per-million per micrometer of pathlength through which the light, for example UV light, travels toactivate the photochromic dye in the article. In general, there will bea similar amount of binder present to the total amount of colorants andmodifiers in the dispersed phase.

In certain embodiments, in the dispersed phase a portion of the bindersmay also serve to modify the microenvironment of the colorants,depending on the details of location of the colorants and binders withinthe dispersed phase. The same functional groups that are effective inmodifying colorant attributes as additives are also effective as part ofthe structural components present as the (co)monomers used to build thebinders comprising the dispersed phase. Such functional groups includehydroxyl and ether groups (R—OH and R_(a)—O—R_(b)), ester groups(R_(a)-[C═O]-OR_(b)), ketone groups (R_(a)-[C═O]-R_(b)), amine groups(R_(a)NHR_(b)), nitro groups (R—NO₂), carbonate groups(R_(a)O—[C═O]-OR_(b)), amide groups (R_(a)NH—[C═O]-R_(b)), urethanegroups (R_(a)NH—[C═O]-OR_(b)), urea groups (R_(a)NH—[C═O]-NHR_(b)),imide groups (R_(a)-[C═O]-NH—[C═O]-R_(b)), hydrazide, semicarbazide andsemicarbazone groups (R_(a)-[C═O]-NH—NHR_(b), R_(a)—NH—[C═O]-NH—NHR_(b)and R_(a)NH—[C═O]-NH—N═CR_(b)R_(c)), thiol and thioether groups (R—SHand R_(a)SR_(b)), sulfoxide and sulfone groups (R_(a)-[S═O]-R_(b) andR_(a)-[SO₂]-R_(b)), ester groups (R_(a)-[SO₂]-OR_(b)), phosphines andphosphine oxides (R_(a)R_(b)R_(c)P and R_(a)R_(b)R_(c)P═O), esters(R_(a)[R_(b)O]-α[═O]-OR_(c)), phosphate esters [RO]₃P═O), and the like,which are polar (have high dielectric constants) and which can interactwith the photochromic dyes by donating and/or accepting hydrogen bonds.

In addition to these binder functional groups acting to modify the localmicroenvironment around colorants to alter their performance attributesvia through space (dipole-dipole) or direct interactions (such ashydrogen bonding), the (co)monomers can be selected to change the binderglass transition temperature, which also modifies photochromic dyeresponse. In general, if the binder glass transition temperature issubstantially higher than the ambient temperature at which the light isabsorbed and activates the photochromic dye, the color transformationswill be slower than if the binder glass transition temperature issimilar to or substantially below the ambient temperature ofirradiation. Since the ambient temperature also affects the rate of thereverse reaction of the photochromic dye back to its leuco form (k₂), abinder with a glass transition temperature similar to or slightly higherthan the ambient temperature can serve to increase the concentration ofthe colored form of the photochromic dye during UV activation,increasing optical density (see FIG. 2 at 15 minutes).

A further characteristic of the dispersed phase binder systems is theirdetailed morphological or structural features. The binder systems of agiven species of dispersed phase particle can be homogeneous orheterogeneous, where the heterogeneity can be on a molecular scale, suchas in interpenetrating polymer networks, or on a larger scale,particularly where it is radial, i.e. the binder composition varies as afunction of distance from the center of the dispersed phase particle.Such a structure has been referred to as a core-shell particle, wherethe outermost surface of the particle (the shell) has a chemicalcomposition distinctly different from the innermost part of the particle(the core). The transition zones between the different radialcompositions can be a tapered or gradient zone, where the composition ofthe binder changes gradually (over several to many covalent bondlengths) as the distance from the center of the dispersed phase particleincreases, or a step change zone, where the composition of the binderchanges suddenly over a short distance (on the order of a few to severalcovalent bond lengths).

In certain embodiments of the present invention, the modifiers employedin the dye matrix are confined or contained within the dispersed phaseby crosslin king the core and/or particularly the shell with themodifiers. Alternatively, the modifiers employed in the dye matrix areconfined or contained within the dispersed phase by selection based uponmiscibility with the core but not the continuous phase, i.e.partitioning of the modifier.

In certain embodiments, polyisocyanate-containing monomers and oligomersare employed as binders in the dispersed phase. Aromatic isocyanates aremore reactive with water, but their reaction with water will provideamine groups, which are co-reactive with isocyanates (forming urealinkages), and will lead to formation of higher molecular weightspecies. Their higher water reactivity compared to aliphatic isocyanatesmay complicate structural and molecular weight control of the oligomersor polymers within the core particles if the prepolymers are created inemulsion particles. For example, they can be used to pre-form highermolecular weight species (prepolymers) in an essentially water-freestep, followed by their subsequent emulsification and interfacialreaction with water-soluble co-reactants.

Alternatively aliphatic isocyanates are less water-reactive, whichallows better control of the molecular structures of the core particlecomponents. In a similar manner, aliphatic isocyanates may be used topre-form isocyanate-terminated prepolymers by reaction with non- orminimally water soluble co-reactants, which can subsequently beemulsified to form the core or seed particles, followed by interfacialpolymerization with the fully water soluble co-reactants to form theshell. Alternatively, the aliphatic isocyanate monomers/oligomers andsuitable co-reactants can be emulsified and allowed to form theisocyanate-terminated prepolymers in-situ prior to interfacial reactionwith water soluble co-reactants to form the shell.

As a further provision, the formation of isocyanate prepolymers can beaccomplished in the presence or absence of solvents, for example waterinsoluble solvents such as toluene, butyl acetate, and the like, whichhelp solubilize other components whose presence in the emulsion core(seed) particles is desired, such as dyes or other functional additives(catalysts, antioxidants, etc.), as well as the co-reactants, such as(largely) water-insoluble polyols, for example polycaprolactone diolsand minor amounts of water insoluble crosslinkers (containing 3 or moreisocyanate-reactive end groups). The solvent may also reduce theviscosity of the prepolymer mixture, simplifying its subsequentemulsification.

A key attribute of the dispersed phase is the average size of theparticles containing the colorants and their adjuvants. If the articleis transparent and used in an optical device, the dispersed phaseparticles may be less than about 200 nanometers in diameter, less thanabout 100 nanometers in diameter, or less than about 50 nanometers indiameter. If the article is a surface coating applied for aesthetic ormarking purposes, such as for example inks or decorative coatings, theparticles can be larger.

There is no restriction to the use of a single colorant in the dispersedphase. More than one type of dye-containing dispersed phase can bepresent within the continuous phase, with each type comprise one or morephotochromic dyes, permanent dyes or pigments to further modify thecolor of the final article. Thus, the dispersed phase can be comprisedof a mixture of dispersed phases, each type with a differentcharacteristic color, temperature sensitivity, activation or fading ratebased on the colorants. Additionally, where a permanent color is desiredin the unactivated state, non-photochromic colorants can be present in aportion of the dispersed phase, in the absence of a photochromic dyecomponent. Use of such dispersed phases will provide articles with no orsome color under normal visible light, which adopt an additional colorafter UV irradiation, and which will fade over time after removal of theactivating UV light source back to the original colorless or coloredstate.

The amount of colorant, for example, photochromic dye, present in thedispersed phase is be sufficient to provide the desired degree ofactivated color formation (optical density or percent transmittance)within the article. As such, the photochromic dye present may be fromabout 100 parts-per-million per micrometer to about 5,000parts-per-million per micrometer of path length through which the lighttravels to activate the photochromic dye in the article. This amount mayvary by dye type, its molecular weight and extinction coefficient andthe amount of color change desired, if dynamic, and the presence ofother colorants such as permanent dyes or pigments, and their extinctioncoefficients.

The relationship between the amount of the dispersed colorant-containingphase and the continuous phase is analogous to the pigment volumeconcentration (PVC) commonly used to characterize decorative andprotective coatings. This is defined as the percent volume occupied bythe combined dispersed phases (the pigments plus fillers) relative tothe total volume of the dried coating (total dispersed plus continuousphases=100 percent). Depending on the particulars of the formulation(pigment type and particle size distribution, resin/binder type, solventvs water borne vs solventless coatings), the critical PVC (CPVC) is thatpoint where there is just enough binder to completely wet-out thepigment. This value can vary from the mid 40 percent range up to morethan 65 percent (approaching the theoretical limit for polydispersespherical particles). Above the CPVC, the coating is less mechanicallysound and more porous, while below the CPVC, the coating exhibitsproperties more characteristic of the unpigmented binder components.

Accordingly, the optimal volume of dispersed phase is below the CPVC forthe combined dispersed colorant-containing phases and continuous hostmatrix phase mixture. This regime is where the properties of thecontinuous host matrix phase dominate the mechanical properties of thecomposition, and the dispersed colorant-containing phases are primarilyimportant for their aesthetic contributions. As such, in this regime,the continuous and dispersed phases can be optimized independently forthe end use. For example, the continuous phase can be optimized foradhesion to a substrate, flexibility, moisture and temperatureresistance, etc. while the dispersed phase can be optimized for itscolor response attributes. In these compositions, where the dispersedphase resembles spherical particles with a narrow polydispersity, thePVC will be less than about 50 percent, or less than about 40 percent.

For dynamic colorants, the amount of for example, photochromic dye isinversely proportional to the volume percent of the dispersed phasecontained within the continuous phase, and depends on the particulardye. For example, if the dispersed phase is 40 volume percent and thecontinuous phase is 60 volume percent, the nominal dye concentrationmust be 2.5 times greater than required to achieve the target opticaldensity than would be required if the dye were uniformly distributedwithin the host or continuous phase. Alternatively, if the dispersedphase is 33 volume percent and the continuous phase is 67 volumepercent, the nominal dye concentration must be 3 times greater thanrequired to achieve the target optical density than would be required ifthe dye were uniformly distributed within the host or continuous phase

The host matrix continuous phase may be comprise monomers, oligomers,(co)polymers, solvents, catalysts, stabilizing additives, processingaids, and the like as required to enable matrix formulation, formationand incorporation of the dispersed phase. In one or more subsequentsteps, the mixture of liquid continuous phase and the dispersed phase isconverted to the final form in which the photochromic properties of thedispersed phase will become incorporated in an article of commerce.

Certain embodiments of the present invention employ compositionscomprising a continuous phase or host matrix in which two or moredifferent dispersed phases particles with photochromic attributes areembedded.

Certain embodiments of the present invention comprise a dispersed phaseshaving one or more colorants, at least a portion of which is aphotochromic dye, one or more microenvironment modifiers and one or morebinder materials to contain the active components that generate theprincipal optical effects.

Certain embodiments of the present invention employ mixtures of separatedispersed phase compositions individually selected to optimizephotochromic dye color, activation and/or decay responses.

Synthesis Example

Step 1: NCO-terminated prepolymer formation. Combined 10.00 g of a 50weight percent solution of CAPA 2101A (polycaprolactone diol) intoluene, 3.14 grams of a 50 weight percent solution of aliphaticdiisocyanate (H₁₂MDI, Desmodure W) and 0.156 grams of a 5 weight percentsolution of dibutyltin dilaurate (T-12 catalyst) at room temperature andallowed to react over two days, forming a clear viscous solution.

Step 2: Emulsification. Combined 3.02 grams of the NCO prepolymersolution of step 1 with 0.50 grams of a 12.5 weight percent solution ofa photochromic dye in toluene and mixed until uniform, forming SolutionA. Combined 4.00 grams of N,N-dimethyl lauramine-N-oxide surfactantsolution in water, 2.00 grams of DI water and 1.50 grams of a 10.5weight percent solution of Selvol Ultilok 5003 (NH₂ modified polyvinylalcohol) in water to form Solution B.

Step 3. All of Solution B was added to all of Solution A and shaken toform a milky emulsion. Mixture was allowed to sit at ambient temperaturefor 2 hours, put into a 65 degrees Celsius oven for 3 hours, and thenrolled overnight at ambient temperature. The final emulsion remainedstable towards settling and the photochromic dye remained active to UVlight.

Step 4. Centrifuged the emulsion and isolated portion of the emulsionparticle solids and then dried the solids on filter paper. Whendispersed in THF, the solids contained active dye and did not dissolve.

Alternative methods may include an additional amount of a waterinsoluble crosslinker added to the prepolymer solution (A) just prior toemulsification with Solution B to further crosslink the particle core.

Use of Encapsulated Dynamically Responsive Dye in ControlledMicroenvironments

Controllable dye characteristics for dynamically responsive colorantsystems according to the present invention include dye color response ofactivation (represented by a* and b* values in FIG. 1), andparticularly, dye rates of activation and fade-back to the leuco(colorless) state (FIG. 2). Another controllable dye characteristic isthe variability of dye response depending on the ambient temperature atwhich the system is externally stimulated.

As exemplified by photochromic dye behavior, in general, a given dyesystem, comprising one dye in one microenvironment/matrix, can achieve ahigher optical density at lower temperatures than it can at elevatedtemperatures due to the combined influence of temperature on dye matrixsegmental motion (relative to dye matrix glass transition temperature)and dye thermal reversion rate to the leuco form as expressed by therate k₂. All chemical reactions are similarly affected by environmenttemperature: reaction rates are higher at higher temperatures and lowerat lower temperatures. This is evident in systems where the temperatureat activation is similar to or below the dye matrix glass transitiontemperature (see FIG. 2 at 15 minutes for samples with glass transitiontemperature of −42° C., −23° C. and +15° C.). Critically, both rates k₁and k₂ depend strongly on the glass transition temperature of the dyemicroenvironment in relation to the ambient temperature at which thesystem was activated. This means that in a microenvironment with a glasstransition temperature higher than the ambient activation temperature,the photochromic system will take longer to reach full activation orfade back to the unactivated color after the activation source isremoved. Conversely, less time is required to interconvert between theleuco and activated state if the microenvironment glass transitiontemperature is below the activation temperature. In this way, the ratesof color change, and the appearance and function of the article, can beadjusted in relation to the typical use temperature range.

Again, as exemplified by photochromic dye behavior, by combiningdispersed phase particles having specific, and different, temperatureresponse rates into a single continuous phase, the behavior of thearticle can be modified to respond in whatever manner is desired. Forexample, combining two types of dispersed phase particles, one with alow glass transition temperature microenvironment and the other with ahigh glass transition temperature microenvironment, will result in aphotochromic system exhibiting a fast initial activation responsefollowed by a gradual increase to the final desired optical density,which will subsequently decrease rapidly to an intermediate level andfade back to the leuco form gradually after removal of the UV activationsource. By varying the ratio of each type of dispersed phase dye systempresent in the continuous host phase, and controlling the specificcharacteristics of the dispersed phase microenvironment, the relativerates of change (k₁ and k₂) and maximum optical density achieved can betailored to the specific application.

Such photochromic compositions as these, as well as other dynamicallyresponsive colorants, can be incorporated in finished articles ofcommerce in a variety of ways, principally as a component in a coating,as a component in a laminated structure, and as a component in a cast,extruded or molded article. Analogous to the use of conventional(permanent or passive) colorants (pigments and dyes) in these articles,mixtures of different dynamically responsive dispersed phases can becombined to fine-tune the aesthetic characteristics of the article, andunlike conventional passive colorants, color response characteristicscan also be easily fine-tuned.

Coated Articles

Coated articles are prepared by application of a coating onto asubstrate. Traditional coatings are typically formulated with an inertvolatile solvent or diluent (organic liquids and/or water) in which aredissolved and/or suspended in a variety of components. Pigments(insoluble permanent colorants) and dyes (soluble permanent colorants)provide the aesthetic character and resinous film forming components(soluble or dispersed binders or vehicles) keep the colorants on thesubstrate and provide the desired mechanical characteristics dictated bythe article's end use conditions. Other components are also generallypresent in a coating and fulfill other functional roles, such ascatalysts to cure thermoset or photoset resins, additives to improve acoating's application characteristics (wetting and adhesion of thecoating to the substrate, bubble release), stabilize the wet composition(towards premature cure, settling and aggregation or supportingbiofouling organisms) or the dried finished coating (towards oxidativeor UV degradation), increase or decrease surface gloss, etc.

Such coatings can be formulated as thermoplastic or thermoset/photosetmaterials. Thermoplastic formulations are distinguished by their lack ofsignificant molecular weight growth after application, whilethermoset/photoset systems are formulated from reactive components thatundergo significant molecular weight growth after application, and whichmay contain reactive solvents or diluents that become a permanent partof the final dried coating. Typically, thermoset compositions are curedthrough exposure to heat, while photoset compositions are cured throughexposure to UV or visible light. These reactive systems generallycontain catalysts that are activated through heat and/or UV or visiblelight irradiation. Still other coatings are applied as thermoplastic orthermoset/photoset powders that are melted on the surface of thesubstrate to form a continuous film.

Coatings can range in applied thickness over a wide range, depending ontheir function, use environment, and the function of the article onwhich they are applied. Decorative coatings are generally applied atlower thickness than functional coatings, but again this depends on thesubstrate and its intended use. The compositions of this invention canbe used in both protective and functional coatings.

As exemplified by photochromic dyes, dispersed phase photochromiccomponents of the types disclosed in this invention can replace some orall of the permanent colorants (pigments or dyes) in the coatings to beused on or in the articles of this invention. These components providefor a dynamic color response of the article to its environment in theform of a response external stimuli, in this case to incident UVradiation. These dispersed phase photochromic components and the coatingbinders can be separately selected and/or formulated to provide thedegree and nature of the performance attributes each type of componentis expected to provide to the finished article.

For example, specific coated articles include transparent substratessuch as ophthalmic lenses, motorsport visors, non-corrective eyewear,sportswear, goggles and windows for architectural and transportation enduses, variable neutral density filters for optical devices, active orpassive graphic display devices, graphic decoration on rigid andflexible substrates such as glass, plastic and metal containers, paper,foil and film for shelf display and product label applications, amongothers. They can also be used in coatings and inks sold use fordecorative and functional purposes on other substrates, includingsporting goods, currency and security applications, fabrics andtextiles, particularly room darkening draperies, curtains, shades andtransparent or translucent films for residential and commercialbuildings, novelty nail polishes, lip gloss, hair sprays, eye shadow andrelated cosmetic applications, and as dynamically responsive colorantssold to manufacturers to be formulated into functional and decorativecoatings to be applied professionally or by consumers to a range ofother substrates.

Laminated Articles

Laminated dynamically responsive colored articles may be prepared byapplication of a photochromic, electrochromic or liquid crystalcontaining coating onto a filmic substrate, which is then incorporatedinto a structure in such a way that the dynamically responsive coatingis not on an outermost surface. Such an illustrative process involvescoating the dynamically responsive composition onto a release liner ordirectly onto a transparent filmic substrate. If coated onto a releaseliner, the coating must be transferred to the filmic substrate to beincorporated into the final article. If directly coated onto the filmicsubstrate, this coated substrate must be incorporated into the finalarticle. Thus, the coated side of the filmic substrate is either coveredwith another filmic substrate, both of which are typically transparent,so as to allow the dynamic response to be visible, or placed in contactwith an external surface of the article by one of several additionalprocess steps.

For example, the original coated filmic substrate can be applied to thesurface of an article or another filmic substrate that is converted tothe final article in one or more conversion process steps, includingmolding. For example, a photochromic coating on a transparent filmicsubstrate can be placed within a mold cavity such that the photochromiccoating is oriented towards the interior of the mold cavity, which issubsequently filled with the material of article construction.Additionally, a photochromic coating, located between two transparentfilmic substrates, can be placed within a mold, and the article made byinjection molding with a molten transparent thermoplastic material or atransparent liquid thermoset material. In these processes, the originallaminate, comprising the photochromic coating, on one or between twotransparent filmic substrates, becomes an outer surface of the article,but the photochromic layer is contained within a laminate structure andprotected from direct contact with the external environment.

Laminates may be manufactured using coatings formulated with inertvolatile solvents, or containing reactive diluents, or by directextrusion of a molten liquid composition directly onto a filmicsubstrate, typically in a roll-to-roll process, among other methods. Ifa volatile solvent is employed, the coated filmic substrate must bedried before the next process step. The coating applied to the filmicsubstrate may be comprise the volatile diluent (organic liquids and/orwater) in which are dissolved and/or suspended a variety of components.The colorants can include the mixed dynamically responsive dispersedphases as described above, pigments (insoluble permanent colorants) anddyes (soluble permanent colorants), which provide the aestheticcharacter of the laminate, and resinous film forming components (solubleor dispersed binders or vehicles), which provide the desired adhesiveand mechanical characteristics dictated by the article's end useconditions. Additional components can also be present to fulfill otherfunctional roles, such as catalysts to cure thermoset or photosetresins, to improve application characteristics, such as wetting,flow-out and adhesion of the coating to the substrate, or bubblerelease, stabilize the liquid composition towards premature cure,settling and aggregation of the dispersed phase or supporting biofoulingorganisms prior to application to the filmic substrate—for long termstorage or pot-life considerations, or to stabilize the dried finishedcoating towards oxidative or UV degradation, etc. in the end useapplication.

Such laminates can be formulated with thermoplastic, thermoset orphotoset interlayer binders between the transparent filmic substrates,which binders carry the dispersed phase dynamically responsivecolorants. Thermoplastic formulations are distinguished by their lack ofsignificant molecular weight growth after application, and willgenerally contain a volatile component, or may be applied by extrusionin a molten state. In the event that a volatile solvent is employed forcoating application to the filmic substrate, it must be driven from thecoating prior to further process steps. Thermoset and photoset systemsare formulated from reactive components that undergo significantmolecular weight growth after application, and which may containvolatile solvents which must be driven from the coating prior to thenext process steps, or reactive solvents or diluents that become apermanent part of the final dried coating.

For example, specific laminated articles include transparent substratessuch as ophthalmic lenses and windows for architectural andtransportation end uses, variable neutral density filters for opticaldevices, active or passive graphic display devices, graphic decorationon rigid and flexible substrates such as glass, plastic and metalcontainers, paper, foil and film for shelf display and product labelapplications, among others. They can be sold and used in transparent ortranslucent roll or sheet form for further conversion to dynamicallyresponsive articles, including decorative and functional purposes onother substrates, such as in sporting goods, as a component in varioussecurity and anti-counterfeiting measures, fabrics and textiles,particularly in structures intended for use as room darkening draperies,curtains, shades and films for residential and commercial buildings, andas dynamically responsive colorants sold to manufacturers to beformulated into dynamically responsive functional and decorativelaminates.

Molded and Extruded Articles

Molded and extruded dynamically responsive articles may be prepared byincorporation of one or more dynamically responsive dispersed phasesinto transparent or translucent molding resins, which are then convertedinto a molded or extruded article. An illustrative process involvesblending a photochromic dispersed phase with a molding resin, such as atransparent liquid thermoset composition, filling a mold with thecombined composition, and curing the liquid mixture to form a solidtransparent article, such as an ophthalmic lens.

The dynamically responsive molding resin may be comprise variety ofcomponents. The colorants can include the mixed dynamically responsivedispersed phases as described above, pigments (insoluble permanentcolorants) and dyes (soluble permanent colorants), which togetherprovide the aesthetic and/or functional character in the molded article,and resinous components, which provide the desired mechanicalcharacteristics dictated by the article's end use conditions. Additionalcomponents can also be present to fulfill other functional roles, suchas catalysts to cure thermoset or photoset resins, additives thatimprove process characteristics, such as resin rheology andmold-release, stabilize a liquid thermoset or photoset compositiontowards premature cure or settling of the dispersed phase prior tomolding—for long term storage or pot-life considerations, or tostabilize the finished article towards oxidative or UV degradation, etc.in the end use application.

Such molded articles can be formulated from thermoplastic, thermoset orphotoset resinous compositions. Thermoplastic formulations aredistinguished by their lack of significant molecular weight growth aftermolding, and will generally be formed into articles by injection moldingor extrusion in a molten state. Thermoset and photoset systems areformulated from reactive components that undergo significant molecularweight growth during or subsequent to molding or extruding, and whichmay contain reactive solvents or diluents that become a permanent partof the final molded or extruded article in addition to higher molecularweight oligomeric or resinous components.

Specific examples of molded articles include transparent compositionssuch as ophthalmic lenses and windows for architectural andtransportation end uses, variable neutral density filters for opticaldevices, and as containers for light sensitive contents. Dynamicallyresponsive compositions can also be extruded into fibers for conversioninto novelty fabrics and textiles for apparel, and particularlyfunctional fabrics and textiles for room darkening draperies, curtainsand shades, or transparent or translucent molded sheet or roll form forfurther conversion to photochromic articles, including for decorativeand functional purposes when combined with other substrates, orconverted directly to sporting goods and accessories, security oranti-counterfeiting devices. Thermoplastic, thermoset or photosetcompositions containing dynamically responsive dispersed phase colorantscan also be converted by molding or extrusion into amusing novelties(beads, rings, bracelets, buttons, combs, hair clips, visors and hatbrims, umbrellas, doll hair, etc.), and toys, artificial fingernails,and the like, which will change color when exposed to the appropriateexternal stimulus, which activates the color change.

Certain embodiments of the present invention comprise a continuous phasehost matrix in which a dispersed phase with dynamically responsiveattributes is embedded.

Certain dispersed phases according to the present invention comprise oneor more colorants, at least a portion of which is a photochromic dye,one or more microenvironment modifiers and one or more binder materialsto contain the active components that generate the principal opticaleffects.

Certain dispersed phases according to the present invention comprise oneor more colorants, at least a portion of which is an electrochromic dye,one or more microenvironment modifiers and one or more binder materialsto contain the active components that generate the principal opticaleffects.

Certain dispersed phases according to the present invention comprise oneor more colorants, at least a portion of which is a liquid crystal dye,one or more microenvironment modifiers and one or more binder materialsto contain the active components that generate the principal opticaleffects.

Certain embodiments of the present invention comprise coatings,laminates, extruded and/or molded articles fabricated from a continuousphase host matrix in which a dispersed phase with dynamically responsiveattributes is embedded.

Certain coatings according to the present invention are thermoplastic,thermoset or photoset.

Certain embodiments of the present invention comprise coated articlesmade with a continuous phase host matrix in which a dispersed phase withdynamically responsive attributes is embedded.

Certain coated articles according to the present invention comprise athermoplastic, thermoset and/or photoset coating.

Certain coated articles according to the present invention aretransparent.

Certain coated articles according to the present invention aretranslucent.

Certain coated articles according to the present invention are opticallyclear.

Certain coated articles according to the present invention areophthalmic lenses.

Certain coated articles according to the present invention arenon-corrective eyewear, goggles or visors.

Certain coated articles according to the present invention are windows.

Certain coated articles according to the present invention are activedisplays.

Certain coated articles according to the present invention are usercontrolled by user input.

Certain coated articles according to the present invention aredynamically responsive to their environment.

Certain laminates according to the present invention are thermoplastic,thermoset or photoset.

Certain embodiments of the present invention comprise coated articlesmade with a continuous phase host matrix in which a dispersed phase withdynamically responsive attributes is embedded.

Certain laminated articles according to the present invention aretransparent.

Certain laminated articles according to the present invention aretranslucent.

Certain laminated articles according to the present invention areoptically clear.

Certain laminated articles according to the present invention areophthalmic lenses.

Certain laminated articles according to the present invention arenon-corrective eyewear, goggles or visors.

Certain laminated articles according to the present invention arewindows.

Certain laminated articles according to the present invention are activedisplays.

Certain laminated articles having active displays according to thepresent invention are user controlled by user input.

Certain laminated articles having active displays according to thepresent invention are dynamically responsive to their environment.

Certain extrudates according to the present invention are thermoplastic,thermoset and/or photoset.

Certain extrudates according to the present invention are fibers orfilms.

Certain embodiments of the present invention comprise extruded articlesmade with a continuous phase host matrix in which a dispersed phase withdynamically responsive attributes is embedded.

Certain extruded articles according to the present invention are fibers,fabrics or textiles.

Certain embodiments of the present invention comprise finished articlesthat are made with fibers, fabrics or textiles.

Certain embodiments of the present invention comprise molded articlesmade with a continuous phase host matrix in which a dispersed phase withdynamically responsive attributes is embedded.

Certain molded articles according to the present invention aretransparent.

Certain finished molded articles according to the present invention aretransparent.

Certain finished molded articles according to the present invention aretranslucent.

Certain finished molded articles according to the present invention areoptically clear.

Certain finished molded articles according to the present invention arenon-corrective eyewear, goggles or visors.

Certain finished molded articles according to the present invention areophthalmic lenses.

Certain finished molded articles according to the present invention arewindows.

Certain finished molded articles according to the present invention areactive displays.

Certain molded articles having active displays according to the presentinvention are user controlled by user input.

Certain molded articles having active displays according to the presentinvention are dynamically responsive to their environment.

Certain molded articles according to the present invention arecontainers or packaging.

Certain molded articles according to the present invention aretransparent or translucent.

Certain molded articles according to the present invention are toys ornovelties.

Certain molded articles according to the present invention are wearablefashion or functional accessories.

Certain molded articles according to the present invention arenon-corrective eyewear, goggles or visors or hat-brims, beads, rings,bracelets, buttons, combs, hair clips, umbrellas, doll hair, artificialfingernails or toys.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A method for optimization of a photochromic dyecomprising: optimizing a characteristic of a photochromic dye within acomposition; isolating the composition containing the photochromic dyewith in a particle; and encapsulating the particle within a host phasematerial distinct from the composition containing the photochromic dye.2. The method of claim 1 wherein the step of optimizing a characteristicof a photochromic dye within a composition comprises controlling a glasstransition temperature of the composition.
 3. The method of claim 1wherein the step of optimizing a characteristic of a photochromic dyewithin a composition comprises controlling a polarity of thecomposition.
 4. The method of claim 1 wherein the step of optimizing acharacteristic of a photochromic dye within a composition comprisesoptimizing a rate of color change of the photochromic dye.
 5. The methodof claim 1 wherein the step of optimizing a characteristic of aphotochromic dye within a composition comprises optimizing a neutralcolor tone of the photochromic dye.
 6. The method of claim 1 wherein thestep of isolating the composition containing the photochromic dye within a particle comprises forming a polymeric shell around the compositioncontaining the photochromic dye.
 7. The method of claim 1 wherein thestep of encapsulating the particle within a host phase material distinctfrom the composition containing the photochromic dye comprisesdispersing the particle within a layer of a transparent material.
 8. Aoptical article comprising: a host phase having a first glass transitiontemperature; and a dispersed phase distinct from the host phase, thedispersed phase distributed within the host phase, the dispersed phasecomprising an inner matrix having at least one photochromic dye and asecond glass transition temperature different from the first glasstransition temperature.
 9. The optical article of claim 8 wherein thehost phase is a thermoset resinous layer.
 10. The optical article ofclaim 8 wherein the host phase is a thermoplastic resinous layer. 11.The optical article of claim 8 wherein the dispersed phase comprises apolymeric binder.
 12. The optical article of claim 8 wherein thedispersed phase comprises an outer shell insoluble in the host phase.13. The optical article of claim 8 wherein the first glass transitiontemperature is higher than the second glass transition temperature. 14.The optical article of claim 8 wherein the photochromic dye is anaphthopyran.
 15. A photochromic layer comprising: a dispersed phaseparticle distributed within a host phase medium; the dispersed phasecomprising an inner matrix that is substantially isolated from the hostphase medium; the inner matrix containing at least one photochromic dye.16. The photochromic layer of claim 15 wherein the dispersed phasecomprises a particle.
 17. The photochromic layer of claim 15 wherein thedispersed phase comprises a shell formed of an isocyanate-terminatedprepolymer.
 18. The photochromic layer of claim 15 wherein the innermatrix comprises a plasticizer.
 19. The photochromic layer of claim 15wherein the host phase medium comprises a dye distinct from the at leastone photochromic dye.
 20. The photochromic layer of claim 15 wherein theinner matrix comprises a solvent type modifier.